Known from the state of the art are a series of radio modules, which serve for retrofitting a field device with a radio module and, thus, for providing for wireless communication with the field device.
For example, one such radio module is disclosed in EP 1754116 B1, which radio module is connectable releasably with the sensor electronics of the field device at a field device interface or a conventional digital switch output.
Further known from EP 1442338 B1 is an apparatus composed of a radio module and a field device, wherein the radio module is connectable to a fieldbus interface of the field device.
Furthermore, it is known to provide the radio module with an energy supply, by means of which the connected field device can be supplied with electrical energy. The energy supply occurs, in such case, via an energy source with limited capacitance or capacity, such as, for example, a single-use battery or a rechargeable battery.